Wave-wave interaction in plasmas is a topic of important research since the16th century. The formation of Langmuir solitons through the coupling ofhigh-frequency (hf) Langmuir and low-frequency (lf) ion-acoustic waves, is oneof the most interesting features in the context of turbulence in modern plasmaphysics. Moreover, quantum plasmas, which are ubiquitous in ultrasmallelectronic devices, micromechanical systems as well as in dense astrophysicalenvironments are a topic of current research. In the light of notable interestsin such quantum plasmas, we present here a theoretical investigation on thenonlinear interaction of quantum Langmuir waves (QLWs) and quantum ion-acousticwaves (QIAWs), which are governed by the one-dimensional quantum Zakharovequations (QZEs). It is shown that a transition to spatiotemporal chaos (STC)occurs when the length scale of excitation of linear modes is larger than thatof the most unstable ones. Such length scale is, however, to be larger(compared to the classical one) in presence of the quantum tunneling effect.The latter induces strong QIAW emission leading to the occurrence of collisionand fusion among the patterns at an earlier time than the classical case.Moreover, numerical simulation of the QZEs reveals that many solitary patternscan be excited and saturated through the modulational instability (MI) ofunstable harmonic modes. In a longer time, these solitons are seen to appear inthe state of STC due to strong QIAW emission as well as by the collision andfusion in stochastic motion. The energy in the system is thus stronglyredistributed, which may switch on the onset of Langmuir turbulence in quantumplasmas.
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